The present invention is generally a novel powered ratchet head design. More specifically, the present invention is a ratchet head design having external features for retaining the ratchet mechanism within the head.
Various powered ratchet wrench designs have been designed, manufactured and marketed. As shown in FIG. 1, the prior art design is shown at 10 having a head portion 12 and a handle portion 14. Within head portion 12 is a ratchet mechanism 16, which is enclosed within a yoke 18. Handle portion 14 includes a housing 20 which encloses a drive motor, not shown. Generally, such drive motors have been pneumatic, but other motors have been utilized. The end of handle portion 14 contains a compressed air inlet port 22, which connects to a compressed air supply by various means known in the art. An actuation button or lever 24 is located between air inlet port 22 and housing 20, which allows the operator to actuate the pneumatic motor, the drive mechanism (not shown) and ratchet mechanism 16.
As shown in FIG. 2, the prior art ratchet mechanism 16 contains a shift lever 25, a pawl 28 and a ratchet body 30 having a drive square 26. Alternatively, ratchet mechanism 16 may contain more than one pawl 28. Ratchet mechanism 16 fits within yoke 18 in order to allow for rotation of drive square 26 caused by interaction of pawl 28 and the teeth formed on yoke 18.
When assembled, ratchet mechanism 16 is retained within ratchet head 12 on one end by ear 11 of ratchet housing 12, which is in contact with the upper end of ratchet body 30, opposite drive square 26, and on the other end by an internal snap ring 32, which fits within a groove 34 formed within ear 13, of ratchet head 12. Between snap ring 32 and the lower end of ratchet body 30 is provided a tensioning means, such as a compressed belleville spring washer 31, for example. The belleville spring washer or belleville washer 31, is held in a compressed state between the lower end of ratchet body 30 and snap ring 32. Compressed belleville washer 31 biases ratchet body 30 toward ear 11 of head portion 12 and provides friction for ratchet mechanism 16. This friction is commonly referred to in the art as head tension or simply tension, and allows for advancement of ratchet mechanism 16 within yoke 18, as yoke 18 moves with reciprocating motion within ratchet head 12.
Because the ratchet mechanism 16 is retained internally within ratchet housing 12 between ears 11 and 13, when torque is applied to the ratchet head, the ears 11, 13 of ratchet head 12 begin to widen apart or spread. Upon repeated application of torque to ratchet head 12, ears 11 and 13 may remain in a spread position. This causes ratchet mechanism 16 to function improperly and slip upon application of force to drive square 26 because ears 11 and 13 no longer hold the tensioning means in a compressed state, and the resulting loss of tension between the tensioning means, for example a belleville spring washer, and the ears 11 and 13 does not allow ratchet mechanism 16 to advance within yoke 18. This is a significant problem in prior art ratchet head designs and increases the costs to maintain these ratchet wrenches for both the end user/owner and the ratchet wrench manufacturers.
Therefore, there is a need for an improved ratchet head design which prevents spreading of the ratchet head ears and thus, maintains proper operation of the ratchet mechanism of the pneumatic ratchet wrench.
It is a general object of the present invention to provide a powered ratchet wrench design which prevents spreading of the ratchet head, and thus proper operation of the ratchet wrench.
It is another object of the present invention to provide a powered ratchet wrench design which contains components which are easily replaceable upon excess wear.
It is yet another object of the present invention to provide a powered ratchet wrench that has decreased maintenance costs.
These and other objects of the present invention are accomplished by providing a ratchet head design which externally captures the ratchet mechanism between the ears of the ratchet head. Capturing the ratchet mechanism externally prevents the ears from spreading. The present invention also provides easily and rather inexpensively replaceable wear washers positioned adjacent the wear surfaces of the ratchet head. Through the prevention of spreading of the ratchet head and having replaceable wear surfaces, the life of the tool is increased.